For a device that allows an observer to recognize a stereoscopic image, there is known a 3D image display device including an image generating unit for displaying an image for left eye and an image for right eye on different areas and a polarizing-axis control plate that emits linearly-polarized lights whose polarizing axes of polarized lights incident on two different areas intersect with each other at right angles or circularly-polarized lights whose polarizing axes are rotated in opposite directions (see Patent Documents 1 to 5).